Lung Macrophage Phenotypes and Functional Responses: Role in the Pathogenesis of COPD

New therapeutic targets for the prevention of infectious acute exacerbations of COPD: role of epithelial adhesion molecules and inflammatory pathways

Chronic respiratory diseases are among the leading causes of mortality worldwide, with the major contributor, chronic obstructive pulmonary disease (COPD) accounting for approximately 3 million deaths annually. Frequent acute exacerbations (AEs) of COPD (AECOPD) drive clinical and functional decline in COPD and are associated with accelerated loss of lung function, increased mortality, decreased health-related quality of life and significant economic costs. Infections with a small subgroup of pathogens precipitate the majority of AEs and consequently constitute a significant comorbidity in COPD. However, current pharmacological interventions are ineffective in preventing infectious exacerbations and their treatment is compromised by the rapid development of antibiotic resistance. Thus, alternative preventative therapies need to be considered. Pathogen adherence to the pulmonary epithelium through host receptors is the prerequisite step for invasion and subsequent infection of surrounding structures. Thus, disruption of bacterial-host cell interactions with receptor antagonists or modulation of the ensuing inflammatory profile present attractive avenues for therapeutic development. This review explores key mediators of pathogen-host interactions that may offer new therapeutic targets with the potential to prevent viral/bacterial-mediated AECOPD. There are several conceptual and methodological hurdles hampering the development of new therapies that require further research and resolution.

The Notch ligand DNER regulates macrophage IFNγ release in chronic obstructive pulmonary disease

BACKGROUND

Chronic Obstructive Pulmonary Disease (COPD) is the third leading cause of death worldwide with no curative therapy. A non-canonical Notch ligand, DNER, has been recently identified in GWAS to associate with COPD severity, but its function and contribution to COPD is unknown.

METHODS

DNER localisation was assessed in lung tissue from healthy and COPD patients, and cigarette smoke (CS) exposed mice. Microarray analysis was performed on WT and DNER deficient M1 and M2 bone marrow-derived macrophages (BMDM), and gene set enrichment undertaken. WT and DNER deficient mice were exposed to CS or filtered air for 3 day and 2 months to assess IFNγ-expressing macrophages and emphysema development. Notch and NFKB active subunits were quantified in WT and DNER deficient LPS-treated and untreated BMDM.

FINDINGS

Immunofluorescence staining revealed DNER localised to macrophages in lung tissue from COPD patients and mice. Human and murine macrophages showed enhanced DNER expression in response to inflammation. Interestingly, pro-inflammatory DNER deficient BMDMs exhibited impaired NICD1/NFKB dependent IFNγ signalling and reduced nuclear NICD1/NFKB translocation. Furthermore, decreased IFNγ production and Notch1 activation in recruited macrophages from CS exposed DNER deficient mice were observed, protecting against emphysema and lung dysfunction.

INTERPRETATION

DNER is a novel protein induced in COPD patients and 6 months CS-exposed mice that regulates IFNγ secretion via non-canonical Notch in pro-inflammatory recruited macrophages. These results provide a new pathway involved in COPD immunity that could contribute to the discovery of innovative therapeutic targets.

FUNDING

This work was supported from the Helmholtz Alliance 'Aging and Metabolic Programming, AMPro'.

The Interplay Between Immune Response and Bacterial Infection in COPD: Focus Upon Non-typeable Haemophilus influenzae

Chronic obstructive pulmonary disease (COPD) is a debilitating respiratory disease and one of the leading causes of morbidity and mortality worldwide. It is characterized by persistent respiratory symptoms and airflow limitation due to abnormalities in the lower airway following consistent exposure to noxious particles or gases. Acute exacerbations of COPD (AECOPD) are characterized by increased cough, purulent sputum production, and dyspnea. The AECOPD is mostly associated with infection caused by common cold viruses or bacteria, or co-infections. Chronic and persistent infection by non-typeable Haemophilus influenzae (NTHi), a Gram-negative coccobacillus, contributes to almost half of the infective exacerbations caused by bacteria. This is supported by reports that NTHi is commonly isolated in the sputum from COPD patients during exacerbations. Persistent colonization of NTHi in the lower airway requires a plethora of phenotypic adaptation and virulent mechanisms that are developed over time to cope with changing environmental pressures in the airway such as host immuno-inflammatory response. Chronic inhalation of noxious irritants in COPD causes a changed balance in the lung microbiome, abnormal inflammatory response, and an impaired airway immune system. These conditions significantly provide an opportunistic platform for NTHi colonization and infection resulting in a "vicious circle." Episodes of large inflammation as the consequences of multiple interactions between airway immune cells and NTHi, accumulatively contribute to COPD exacerbations and may result in worsening of the clinical status. In this review, we discuss in detail the interplay and crosstalk between airway immune residents and NTHi, and their effect in AECOPD for better understanding of NTHi pathogenesis in COPD patients.

Systematic analysis of transcriptomic profiles of COPD airway epithelium using next-generation sequencing and bioinformatics

Introduction

COPD is a chronic inflammatory disease of lung. The inflammatory response in COPD is associated with neutrophils, macrophages, T lymphocytes, and bronchial epithelial cells, and occurs mainly in the small airway, leading to irreversible airflow limitation.

Methods

In order to investigate the microRNA–mRNA interaction in the microenvironment of the COPD airway, we used next-generation sequencing and bioinformatics in this study.

Results

We identified four genes with microRNA–mRNA interactions involved in COPD small-airway bronchial epithelial cells: NT5E, SDK1, TNS1, and PCDH7. Furthermore, miR6511a-5p–NT5E interaction was found to be involved in small-airway bronchial epithelial cells, large-airway bronchial epithelial cells, and alveolar macrophages.

Conclusion

Our results showed that miR6511a-5p–NT5E interaction plays an important role in COPD, which might be associated with cell–cell contact, activation of leukocytes, activation of T lymphocytes, and cellular homeostasis. These findings provide new information for further investigations of the COPD microenvironment, and may help to develop new diagnostic or therapeutic strategies targeting the bronchial epithelium for COPD.

Ulinastatin protects the lungs of COPD rats through the HMGB1/TLR4 signaling pathway

The present study aimed to investigate the protective mechanism of ulinastatin against lung injury. Rat models with chronic obstructive pulmonary disease (COPD) were used to provide guidance for the medical treatment of this disease. The rats were divided into three groups: A control group, a model group and an experimental group (each, n=10). With the exception of the control group, all of the rats were prepared as models of COPD, using the composite molding method of smoking and intratracheal instillation of lipopolysaccharide. The rats in the model group all received a conventional treatment, while the rats in the experimental group received ulinastatin. A small animal lung function detector was used to examine lung function. The forced expiratory volume/sec (FEV) was negatively correlated with the protein expression levels of Toll-like receptor 4 (TLR4) and high mobility group box protein 1 (HMGB1). Real-time fluorescence quantitative polymerase chain reaction and western blot analyses were used to detect TLR4, MyD88 (myeloid differentiation factor 88), TRAF-6 (TNF receptor-associated factor 6), LOX-1 (lectin-type oxidized LDL receptor 1) and HMGB1 mRNA, along with their protein expression levels. The lung function of rats in the model group was significantly decreased compared with in the control group (P<0.05). In the experimental group the lung function was significantly greater, when compared with in the model group; however, it remained lower than in the control group. The mRNA and protein expression levels of TLR4, MyD88, TRAF-6, LOX-1 and HMGB1 were significantly higher in the model group than in the control and experimental groups; however, levels in the experimental group were significantly higher when compared with in the control group (P<0.05). The TLR4 and HMGB1 expression levels were positively correlated in all groups, which indicated involvement of the HMGB1/TLR4 signaling pathway. The FEV was negatively correlated with the protein expression levels of TLR4 and HMGB1. Thus, the protective effect of ulinastatin in the lungs of rats with COPD is associated with changes in the HMGB1/TLR4 signaling pathway.